Diff: src/Cortex-M4-M3/FilteringFunctions/arm_fir_lattice_f32.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/FilteringFunctions/arm_fir_lattice_f32.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,413 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:	    arm_fir_lattice_f32.c  
+*  
+* Description:	Processing function for the floating-point FIR Lattice filter.  
+*  
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* Version 1.0.3 2010/11/29 
+*    Re-organized the CMSIS folders and updated documentation.  
+*   
+* Version 1.0.2 2010/11/11  
+*    Documentation updated.   
+*  
+* Version 1.0.1 2010/10/05   
+*    Production release and review comments incorporated.  
+*  
+* Version 1.0.0 2010/09/20   
+*    Production release and review comments incorporated  
+*  
+* Version 0.0.7  2010/06/10   
+*    Misra-C changes done  
+* -------------------------------------------------------------------- */ 
+ 
+#include "arm_math.h" 
+ 
+/**  
+ * @ingroup groupFilters  
+ */ 
+ 
+/**  
+ * @defgroup FIR_Lattice Finite Impulse Response (FIR) Lattice Filters  
+ *  
+ * This set of functions implements Finite Impulse Response (FIR) lattice filters  
+ * for Q15, Q31 and floating-point data types.  Lattice filters are used in a   
+ * variety of adaptive filter applications.  The filter structure is feedforward and  
+ * the net impulse response is finite length.  
+ * The functions operate on blocks  
+ * of input and output data and each call to the function processes  
+ * <code>blockSize</code> samples through the filter.  <code>pSrc</code> and  
+ * <code>pDst</code> point to input and output arrays containing <code>blockSize</code> values.  
+ *  
+ * \par Algorithm:  
+ * \image html FIRLattice.gif "Finite Impulse Response Lattice filter"  
+ * The following difference equation is implemented:  
+ * <pre>  
+ *    f0[n] = g0[n] = x[n]  
+ *    fm[n] = fm-1[n] + km * gm-1[n-1] for m = 1, 2, ...M  
+ *    gm[n] = km * fm-1[n] + gm-1[n-1] for m = 1, 2, ...M  
+ *    y[n] = fM[n]  
+ * </pre>  
+ * \par  
+ * <code>pCoeffs</code> points to tha array of reflection coefficients of size <code>numStages</code>.  
+ * Reflection Coefficients are stored in the following order.  
+ * \par  
+ * <pre>  
+ *    {k1, k2, ..., kM}  
+ * </pre>  
+ * where M is number of stages  
+ * \par  
+ * <code>pState</code> points to a state array of size <code>numStages</code>.  
+ * The state variables (g values) hold previous inputs and are stored in the following order.  
+ * <pre>  
+ *    {g0[n], g1[n], g2[n] ...gM-1[n]}  
+ * </pre>  
+ * The state variables are updated after each block of data is processed; the coefficients are untouched.  
+ * \par Instance Structure  
+ * The coefficients and state variables for a filter are stored together in an instance data structure.  
+ * A separate instance structure must be defined for each filter.  
+ * Coefficient arrays may be shared among several instances while state variable arrays cannot be shared.  
+ * There are separate instance structure declarations for each of the 3 supported data types.  
+ *  
+ * \par Initialization Functions  
+ * There is also an associated initialization function for each data type.  
+ * The initialization function performs the following operations:  
+ * - Sets the values of the internal structure fields.  
+ * - Zeros out the values in the state buffer.  
+ *  
+ * \par  
+ * Use of the initialization function is optional.  
+ * However, if the initialization function is used, then the instance structure cannot be placed into a const data section.  
+ * To place an instance structure into a const data section, the instance structure must be manually initialized.  
+ * Set the values in the state buffer to zeros and then manually initialize the instance structure as follows:  
+ * <pre>  
+ *arm_fir_lattice_instance_f32 S = {numStages, pState, pCoeffs};  
+ *arm_fir_lattice_instance_q31 S = {numStages, pState, pCoeffs};  
+ *arm_fir_lattice_instance_q15 S = {numStages, pState, pCoeffs};  
+ * </pre>  
+ * \par  
+ * where <code>numStages</code> is the number of stages in the filter; <code>pState</code> is the address of the state buffer;  
+ * <code>pCoeffs</code> is the address of the coefficient buffer.  
+ * \par Fixed-Point Behavior  
+ * Care must be taken when using the fixed-point versions of the FIR Lattice filter functions.  
+ * In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.  
+ * Refer to the function specific documentation below for usage guidelines.  
+ */ 
+ 
+/**  
+ * @addtogroup FIR_Lattice  
+ * @{  
+ */ 
+ 
+ 
+  /**  
+   * @brief Processing function for the floating-point FIR lattice filter.  
+   * @param[in]  *S        points to an instance of the floating-point FIR lattice structure.  
+   * @param[in]  *pSrc     points to the block of input data.  
+   * @param[out] *pDst     points to the block of output data  
+   * @param[in]  blockSize number of samples to process.  
+   * @return none.  
+   */ 
+ 
+void arm_fir_lattice_f32( 
+  const arm_fir_lattice_instance_f32 * S, 
+  float32_t * pSrc, 
+  float32_t * pDst, 
+  uint32_t blockSize) 
+{ 
+  float32_t *pState;                             /* State pointer */ 
+  float32_t *pCoeffs = S->pCoeffs;               /* Coefficient pointer */ 
+  float32_t *px;                                 /* temporary state pointer */ 
+  float32_t *pk;                                 /* temporary coefficient pointer */ 
+  float32_t fcurr1, fnext1, gcurr1, gnext1;      /* temporary variables for first sample in loop unrolling */ 
+  float32_t fcurr2, fnext2, gnext2;              /* temporary variables for second sample in loop unrolling */ 
+  float32_t fcurr3, fnext3, gnext3;              /* temporary variables for third sample in loop unrolling */ 
+  float32_t fcurr4, fnext4, gnext4;              /* temporary variables for fourth sample in loop unrolling */ 
+  uint32_t numStages = S->numStages;             /* Number of stages in the filter */ 
+  uint32_t blkCnt, stageCnt;                     /* temporary variables for counts */ 
+ 
+  gcurr1 = 0.0f; 
+  pState = &S->pState[0]; 
+ 
+  blkCnt = blockSize >> 2; 
+ 
+  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
+     a second loop below computes the remaining 1 to 3 samples. */ 
+  while(blkCnt > 0u) 
+  { 
+ 
+    /* Read two samples from input buffer */ 
+    /* f0(n) = x(n) */ 
+    fcurr1 = *pSrc++; 
+    fcurr2 = *pSrc++; 
+ 
+    /* Initialize coeff pointer */ 
+    pk = (pCoeffs); 
+ 
+    /* Initialize state pointer */ 
+    px = pState; 
+ 
+    /* Read g0(n-1) from state */ 
+    gcurr1 = *px; 
+ 
+    /* Process first sample for first tap */ 
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */ 
+    fnext1 = fcurr1 + ((*pk) * gcurr1); 
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */ 
+    gnext1 = (fcurr1 * (*pk)) + gcurr1; 
+ 
+    /* Process second sample for first tap */ 
+    /* for sample 2 processing */ 
+    fnext2 = fcurr2 + ((*pk) * fcurr1); 
+    gnext2 = (fcurr2 * (*pk)) + fcurr1; 
+ 
+    /* Read next two samples from input buffer */ 
+    /* f0(n+2) = x(n+2) */ 
+    fcurr3 = *pSrc++; 
+    fcurr4 = *pSrc++; 
+ 
+    /* Copy only last input samples into the state buffer  
+       which will be used for next four samples processing */ 
+    *px++ = fcurr4; 
+ 
+    /* Process third sample for first tap */ 
+    fnext3 = fcurr3 + ((*pk) * fcurr2); 
+    gnext3 = (fcurr3 * (*pk)) + fcurr2; 
+ 
+    /* Process fourth sample for first tap */ 
+    fnext4 = fcurr4 + ((*pk) * fcurr3); 
+    gnext4 = (fcurr4 * (*pk++)) + fcurr3; 
+ 
+    /* Update of f values for next coefficient set processing */ 
+    fcurr1 = fnext1; 
+    fcurr2 = fnext2; 
+    fcurr3 = fnext3; 
+    fcurr4 = fnext4; 
+ 
+    /* Loop unrolling.  Process 4 taps at a time . */ 
+    stageCnt = (numStages - 1u) >> 2u; 
+ 
+    /* Loop over the number of taps.  Unroll by a factor of 4.  
+     ** Repeat until we've computed numStages-3 coefficients. */ 
+ 
+    /* Process 2nd, 3rd, 4th and 5th taps ... here */ 
+    while(stageCnt > 0u) 
+    { 
+      /* Read g1(n-1), g3(n-1) .... from state */ 
+      gcurr1 = *px; 
+ 
+      /* save g1(n) in state buffer */ 
+      *px++ = gnext4; 
+ 
+      /* Process first sample for 2nd, 6th .. tap */ 
+      /* Sample processing for K2, K6.... */ 
+      /* f2(n) = f1(n) +  K2 * g1(n-1) */ 
+      fnext1 = fcurr1 + ((*pk) * gcurr1); 
+      /* Process second sample for 2nd, 6th .. tap */ 
+      /* for sample 2 processing */ 
+      fnext2 = fcurr2 + ((*pk) * gnext1); 
+      /* Process third sample for 2nd, 6th .. tap */ 
+      fnext3 = fcurr3 + ((*pk) * gnext2); 
+      /* Process fourth sample for 2nd, 6th .. tap */ 
+      fnext4 = fcurr4 + ((*pk) * gnext3); 
+ 
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */ 
+      /* Calculation of state values for next stage */ 
+      gnext4 = (fcurr4 * (*pk)) + gnext3; 
+      gnext3 = (fcurr3 * (*pk)) + gnext2; 
+      gnext2 = (fcurr2 * (*pk)) + gnext1; 
+      gnext1 = (fcurr1 * (*pk++)) + gcurr1; 
+ 
+ 
+      /* Read g2(n-1), g4(n-1) .... from state */ 
+      gcurr1 = *px; 
+ 
+      /* save g2(n) in state buffer */ 
+      *px++ = gnext4; 
+ 
+      /* Sample processing for K3, K7.... */ 
+      /* Process first sample for 3rd, 7th .. tap */ 
+      /* f3(n) = f2(n) +  K3 * g2(n-1) */ 
+      fcurr1 = fnext1 + ((*pk) * gcurr1); 
+      /* Process second sample for 3rd, 7th .. tap */ 
+      fcurr2 = fnext2 + ((*pk) * gnext1); 
+      /* Process third sample for 3rd, 7th .. tap */ 
+      fcurr3 = fnext3 + ((*pk) * gnext2); 
+      /* Process fourth sample for 3rd, 7th .. tap */ 
+      fcurr4 = fnext4 + ((*pk) * gnext3); 
+ 
+      /* Calculation of state values for next stage */ 
+      /* g3(n) = f2(n) * K3  +  g2(n-1) */ 
+      gnext4 = (fnext4 * (*pk)) + gnext3; 
+      gnext3 = (fnext3 * (*pk)) + gnext2; 
+      gnext2 = (fnext2 * (*pk)) + gnext1; 
+      gnext1 = (fnext1 * (*pk++)) + gcurr1; 
+ 
+ 
+      /* Read g1(n-1), g3(n-1) .... from state */ 
+      gcurr1 = *px; 
+ 
+      /* save g3(n) in state buffer */ 
+      *px++ = gnext4; 
+ 
+      /* Sample processing for K4, K8.... */ 
+      /* Process first sample for 4th, 8th .. tap */ 
+      /* f4(n) = f3(n) +  K4 * g3(n-1) */ 
+      fnext1 = fcurr1 + ((*pk) * gcurr1); 
+      /* Process second sample for 4th, 8th .. tap */ 
+      /* for sample 2 processing */ 
+      fnext2 = fcurr2 + ((*pk) * gnext1); 
+      /* Process third sample for 4th, 8th .. tap */ 
+      fnext3 = fcurr3 + ((*pk) * gnext2); 
+      /* Process fourth sample for 4th, 8th .. tap */ 
+      fnext4 = fcurr4 + ((*pk) * gnext3); 
+ 
+      /* g4(n) = f3(n) * K4  +  g3(n-1) */ 
+      /* Calculation of state values for next stage */ 
+      gnext4 = (fcurr4 * (*pk)) + gnext3; 
+      gnext3 = (fcurr3 * (*pk)) + gnext2; 
+      gnext2 = (fcurr2 * (*pk)) + gnext1; 
+      gnext1 = (fcurr1 * (*pk++)) + gcurr1; 
+ 
+      /* Read g2(n-1), g4(n-1) .... from state */ 
+      gcurr1 = *px; 
+ 
+      /* save g4(n) in state buffer */ 
+      *px++ = gnext4; 
+ 
+      /* Sample processing for K5, K9.... */ 
+      /* Process first sample for 5th, 9th .. tap */ 
+      /* f5(n) = f4(n) +  K5 * g4(n-1) */ 
+      fcurr1 = fnext1 + ((*pk) * gcurr1); 
+      /* Process second sample for 5th, 9th .. tap */ 
+      fcurr2 = fnext2 + ((*pk) * gnext1); 
+      /* Process third sample for 5th, 9th .. tap */ 
+      fcurr3 = fnext3 + ((*pk) * gnext2); 
+      /* Process fourth sample for 5th, 9th .. tap */ 
+      fcurr4 = fnext4 + ((*pk) * gnext3); 
+ 
+      /* Calculation of state values for next stage */ 
+      /* g5(n) = f4(n) * K5  +  g4(n-1) */ 
+      gnext4 = (fnext4 * (*pk)) + gnext3; 
+      gnext3 = (fnext3 * (*pk)) + gnext2; 
+      gnext2 = (fnext2 * (*pk)) + gnext1; 
+      gnext1 = (fnext1 * (*pk++)) + gcurr1; 
+ 
+      stageCnt--; 
+    } 
+ 
+    /* If the (filter length -1) is not a multiple of 4, compute the remaining filter taps */ 
+    stageCnt = (numStages - 1u) % 0x4u; 
+ 
+    while(stageCnt > 0u) 
+    { 
+      gcurr1 = *px; 
+ 
+      /* save g value in state buffer */ 
+      *px++ = gnext4; 
+ 
+      /* Process four samples for last three taps here */ 
+      fnext1 = fcurr1 + ((*pk) * gcurr1); 
+      fnext2 = fcurr2 + ((*pk) * gnext1); 
+      fnext3 = fcurr3 + ((*pk) * gnext2); 
+      fnext4 = fcurr4 + ((*pk) * gnext3); 
+ 
+      /* g1(n) = f0(n) * K1  +  g0(n-1) */ 
+      gnext4 = (fcurr4 * (*pk)) + gnext3; 
+      gnext3 = (fcurr3 * (*pk)) + gnext2; 
+      gnext2 = (fcurr2 * (*pk)) + gnext1; 
+      gnext1 = (fcurr1 * (*pk++)) + gcurr1; 
+ 
+      /* Update of f values for next coefficient set processing */ 
+      fcurr1 = fnext1; 
+      fcurr2 = fnext2; 
+      fcurr3 = fnext3; 
+      fcurr4 = fnext4; 
+ 
+      stageCnt--; 
+ 
+    } 
+ 
+    /* The results in the 4 accumulators, store in the destination buffer. */ 
+    /* y(n) = fN(n) */ 
+    *pDst++ = fcurr1; 
+    *pDst++ = fcurr2; 
+    *pDst++ = fcurr3; 
+    *pDst++ = fcurr4; 
+ 
+    blkCnt--; 
+  } 
+ 
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
+   ** No loop unrolling is used. */ 
+  blkCnt = blockSize % 0x4u; 
+ 
+  while(blkCnt > 0u) 
+  { 
+    /* f0(n) = x(n) */ 
+    fcurr1 = *pSrc++; 
+ 
+    /* Initialize coeff pointer */ 
+    pk = (pCoeffs); 
+ 
+    /* Initialize state pointer */ 
+    px = pState; 
+ 
+    /* read g2(n) from state buffer */ 
+    gcurr1 = *px; 
+ 
+    /* for sample 1 processing */ 
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */ 
+    fnext1 = fcurr1 + ((*pk) * gcurr1); 
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */ 
+    gnext1 = (fcurr1 * (*pk++)) + gcurr1; 
+ 
+    /* save g1(n) in state buffer */ 
+    *px++ = fcurr1; 
+ 
+    /* f1(n) is saved in fcurr1  
+       for next stage processing */ 
+    fcurr1 = fnext1; 
+ 
+    stageCnt = (numStages - 1u); 
+ 
+    /* stage loop */ 
+    while(stageCnt > 0u) 
+    { 
+      /* read g2(n) from state buffer */ 
+      gcurr1 = *px; 
+ 
+      /* save g1(n) in state buffer */ 
+      *px++ = gnext1; 
+ 
+      /* Sample processing for K2, K3.... */ 
+      /* f2(n) = f1(n) +  K2 * g1(n-1) */ 
+      fnext1 = fcurr1 + ((*pk) * gcurr1); 
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */ 
+      gnext1 = (fcurr1 * (*pk++)) + gcurr1; 
+ 
+      /* f1(n) is saved in fcurr1  
+         for next stage processing */ 
+      fcurr1 = fnext1; 
+ 
+      stageCnt--; 
+ 
+    } 
+ 
+    /* y(n) = fN(n) */ 
+    *pDst++ = fcurr1; 
+ 
+    blkCnt--; 
+ 
+  } 
+} 
+ 
+/**  
+ * @} end of FIR_Lattice group  
+ */